JP2005026113A - Battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery having a uniform crimp part excellent in sealing capability throughout the entire circumference of an opening of a flat battery case having an oval cross-sectional shape, and excellent in safety because of being formed by applying high-reliability sealing, and never causing electrolyte leakage; and to provide its manufacturing method. <P>SOLUTION: This manufacturing method of this battery comprises: a process for storing a power generation element in the battery case 2 having the oval cross-sectional shape; a process for disposing a sealing member 5 by interlaying a gasket in the opening of the battery case 2; and a sealing process for sealing the opening of the battery case 2 by crimping it inward. In the sealing process, an edge part 2a of each long side surface of the battery case 2 is crimped on a cross-sectionally arc-like molding surface 17, and each edge part 2b of an arc surface for connecting both side end faces of the long side surfaces is crimped on a flat molding surface 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery suitably applied to a battery power source of a small portable electronic device or the like and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, the performance of portable electronic devices such as mobile phones and personal digital assistants depends largely on the performance of not only semiconductor elements and electronic circuits to be mounted but also rechargeable sealed secondary batteries. In addition to increasing the capacity of sealed secondary batteries, it is desirable to simultaneously realize light weight and compact size. As a sealed secondary battery that meets these demands, a nickel-metal hydride storage battery with an energy density approximately twice that of a nickel cadmium storage battery was developed, and then a lithium ion battery that exceeded this was developed, depending on the application of the equipment used. It is properly used.
[0003]
These sealed secondary batteries have a cylindrical, square or flat battery case with a power generation element consisting of an electrode plate group in which a positive electrode plate and a negative electrode plate are wound or stacked in a spiral shape with a separator interposed therebetween and an electrolyte. The battery is configured by being housed and crimped or laser sealed. Among them, a rectangular or flat battery is suitable for thinning the device, and its application to portable electronic devices such as a mobile phone is increasing. As a means of sealing a flat battery, the method of sealing the sealing plate and the case opening by laser welding is a problem that the cost is high and the productivity is poor, and in the case of a lithium secondary battery, an organic electrolyte is used. Therefore, there is a problem that there is a risk of ignition during laser welding.
[0004]
Therefore, a power generation element is housed in an oblong battery case having a long and narrow cross-sectional shape that is inexpensive and excellent in productivity, and a sealing member is disposed in the opening of the battery case via a gasket, so that the opening of the battery case is conventionally provided. As in the case of the cylindrical battery, a method of caulking and sealing is also used. Specifically, in the caulking process of the battery case, as shown in FIG. 5, the recess 22 has the same opening shape as the cross-sectional shape of the battery case, and the same radius of curvature is provided on the outer peripheral portion of the inner bottom surface over the entire circumference. The caulking jig 21 having the arc-shaped molding surface 23 of FIG. 6 is used, and the concave portion 22 of the caulking jig 21 is externally fitted to the opening of the battery case 32 and pressed with a predetermined pressing load. As shown in FIG. 4, the opening portion of the battery case 32 is caulked around the entire circumference to form a caulking portion 33 to seal the battery 31. In FIG. 5, reference numeral 24 denotes an escape recess formed at the center of the inner bottom surface of the recess 22.
[0005]
Specifically, in the battery 31 in which the opening portion of the battery case 32 is caulked using the caulking jig 21 as shown in FIG. 5, the battery case 32 of the caulking portion 33 is included in the caulking portion 33 as shown in FIG. 7. The straight caulking portion 34 at the edge of the long side surface and the arc-shaped caulking portion 35 at the edge portion of the arc surface connecting between both ends of the long side surface of the battery case 32 are compared to the edge portion of the long side surface. Since the end of the arc surface is more easily caulked and sealed, there is a problem that the cross-sectional shapes of the two are different. Furthermore, an abnormal bend 37 due to distortion or buckling due to the difference in the sealing cross-sectional shape between the two may occur in the boundary portion 36 and the vicinity thereof. As a result, it is difficult to ensure the battery sealing performance, that is, the sealing pressure resistance, the sealing strength of the battery sealing portion is reduced, and a safety mechanism such as a current blocking mechanism in the sealing plate that should be activated by an increase in the internal pressure of the battery during overcharging. If the internal pressure drops due to liquid leakage or gas leakage from the sealing part, it may become inoperative, leading to a reduction in battery safety. In addition, such a decrease in sealing pressure resistance has been a serious problem with respect to liquid leakage resistance during high temperature storage.
[0006]
In addition, by forming a flat molding surface on the outer peripheral portion of the inner bottom surface of the concave portion 22 of the caulking jig 21 in place of the molding surface 23 having an arcuate cross section, a linear caulking portion 34 and an arcuate caulking portion 35 are formed. Although it has been considered that buckling does not occur at the boundary portion of the wire, in that case, the caulking reliability in the straight caulking portion 34 is lowered, and there is a possibility that liquid leakage occurs.
[0007]
Therefore, after caulking and sealing with a molding surface having an arc-shaped cross section, a proposal (for example, refer to Patent Document 1) for punching the tip of the battery case on the long side of the upper part of the sealing, or an arc angle on the linear long side There is a proposal (for example, refer to Patent Document 2) that caulking is performed with an arcuate molding surface that is larger than 90 °, and an arc surface connecting both end surfaces of the long side surface is caulking with an arcuate molding surface that is smaller than the arc angle of the long side surface. is there.
[0008]
[Patent Document 1]
JP 2000-331654 A
[0009]
[Patent Document 2]
JP2002-324523
[0010]
[Problems to be solved by the invention]
Even in these cases, since the molding surface having the arc is used for both the linear caulking portion 34 and the arc caulking portion 35, the linear caulking portion 34 and the arcuate shape having different caulking sealing properties are used. The caulking part 35 is not sufficiently sealed, and the battery case is becoming thinner and the gasket is becoming thinner as the capacity and thickness of the battery are increased. This problem becomes increasingly serious. ing.
[0011]
In view of the above-mentioned conventional problems, the present invention has a crimped portion having a uniform and excellent sealing property over the entire circumference of the opening of a flat battery case having an oblong cross-sectional shape, and a highly reliable sealing is achieved. Therefore, an object of the present invention is to provide a battery that is excellent in safety and has no fear of leakage and a method for manufacturing the battery.
[0012]
The battery manufacturing method of the present invention includes a step of housing a power generation element in a battery case having an oblong cross-sectional shape, a step of disposing a sealing member through a gasket in the opening of the battery case, and an opening of the battery case In the battery manufacturing method comprising the sealing step of crimping the inside portion and sealing, the edge of the long side of the battery case in the sealing step is caulked with a molding surface having an arc-shaped cross section, and the ends of both sides of the long side are connected The edge of the arc surface is a manufacturing method that is caulked with a flat molding surface, weakening the caulking and sealing performance of the arc surface edge that is easier to caulch and seal than the edge of the long side, and is equivalent to the long side It can be sealed, and a crimped portion that is uniform and excellent in hermeticity can be formed over the entire periphery of the opening of a flat battery case having an oblong cross-sectional shape including the boundary between the arc surface and the long side surface As a result, the internal pressure of the battery increases during overcharging. The safety mechanism such as the current interruption mechanism in the sealing plate that should be activated is not activated due to a decrease in internal pressure due to liquid leakage or gas leakage from the sealing part, and there is no danger of reducing the safety of the battery. A highly reliable battery with excellent leakage resistance can be produced.
[0013]
Further, in the battery of the present invention, the sealing and crimping edge of the long side of the battery case obtained by the battery manufacturing method has a flat top, and the edge of the arcuate surface connecting between both ends of the long side is The cross-sectional arc shape is preferable, and the height of the edge portion of the arc surface connecting the both side ends of the long side surface is higher than the sealing and caulking end edge portion of the long side surface of the battery case.
[0014]
In this case, even if the edge of the long side is crimped until the apex is flat and the tip is inwardly arcuate or flat, the edge of the arcuate surface connecting both ends of the long side is the insulating gasket The cross section is arc-shaped without buckling, the sealing performance of both can be made equal, and a uniform caulked portion is formed over the entire circumference of the battery case opening including the boundary between the arc surface and the long side surface. Therefore, the safety mechanism such as the current interruption mechanism in the sealing plate that should be activated by the increase in the internal pressure of the battery at the time of overcharge becomes inoperative due to the decrease of the internal pressure due to the liquid leakage or gas leakage from the sealing portion, thus reducing the safety of the battery A highly reliable battery excellent in leakage resistance during high temperature storage can be obtained. Then, the height of the edge of the arc surface connecting the both side ends of the long side surface is higher by 0.1 mm to 0.5 mm than the sealing and caulking end edge portion of the long side surface of the battery case. The compressibility of the insulating gasket on the side surface can be made the same, and the sealing property can be made more uniform.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a battery and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4 using a lithium ion secondary battery. However, the present invention is a flat shape with an oblong cross section. The present invention is not particularly limited, and can be applied to batteries such as a nickel cadmium battery and a nickel metal hydride battery.
[0016]
In FIG. 1, reference numeral 1 denotes a battery made of a lithium ion secondary battery, which has an oblong shape with a transverse cross-sectional shape, and has a flat shape with a thickness dimension of t and a width dimension W of about 4t to 8t. As shown in FIG. 2 and FIG. 3, the battery 1 includes an electrode plate group and an electrolytic solution in which a positive electrode plate and a negative electrode plate are disposed to face each other with a separator in a flat battery case 2 having a bottom open. The battery case 2 can be made of an inexpensive nickel-plated copper plate or a lightweight aluminum alloy depending on the purpose. The opening of the battery case 2 is formed by inserting a sealing plate 5 as a sealing member through an insulating gasket 4 and plastically deforming the opening of the battery case 2 inward over the entire circumference to form a caulking portion 12. It is sealed. Reference numeral 20 denotes a metal reinforcing plate welded and fixed at a predetermined position from the upper end of the opening of the battery case 2 so as to support the sealing plate 5 by laser welding or the like.
[0017]
In the sealing plate 5, the cap 7 having the protruding portion 6 constitutes one polarity connection electrode, and the battery case 2 constitutes the other polarity connection electrode. The sealing plate 5 is configured by accommodating a safety valve mechanism 10, a PTC element 11, and a cap 7 through an inner gasket 9 in the filter 8, the filter 8 is connected to the power generation element 3, and the filter 8 and the cap 7 are safety valves. The mechanism 10 and the PTC element 11 are connected.
[0018]
The caulking portion 12 of the opening of the battery case 2 is configured by a flat caulking portion 13 having a flat surface 13a at the top of the long side edge 2a of the battery case 2, and between the both side ends of the long side of the battery case 2. The edge 2b of the arc surface connecting the two is constituted by an arc caulking portion 14 having an arc cross section.
[0019]
As shown in FIG. 4, the caulking portion 12 has a concave portion 16 having the same opening shape as the cross-sectional shape of the battery case 2, and an arc forming surface 17 and a flat forming surface 18 are formed on the outer peripheral portion of the inner bottom surface thereof. The caulking jig 15 is used, and the concave portion 16 of the caulking jig 15 is externally fitted to the opening of the battery case 2 and is pressed by a predetermined pressing load. The arc forming surface 17 is formed by a forming surface having an arc cross section formed in a straight line portion corresponding to the edge 2a of the long side surface of the battery case 2, and the flat forming surface 18 is an end of the arc surface of the battery case 2. It is comprised by the flat shaping | molding surface formed in the circular arc part corresponding to the edge 2b. The radius of curvature r of the arc forming surface 17 and the radius of curvature r of the corner portion of the flat forming surface 18 are set to be the same. 19a is an escape recess formed at the center of the inner bottom surface of the recess 16, and 19b is a protruding pin for taking out the battery 1 after the caulking process.
[0020]
As described above, in the linear portion of the long side surface of the opening of the battery case 2, the insulating gasket 4 is compressed by being plastically deformed by the arc forming surface 17, and the edge of the battery case 2 is securely caulked and sealed. In the arc portion that connects the ends of both sides of the long side surface, the flat side surface 18 is plastically deformed and caulked inwardly from the outer periphery to the inner periphery of the arc to be sealed and sealed. The edge of the arc surface is flat and the tip is crimped inward or arcuately or planarly, but the insulating gasket does not buckle the edge of the arc surface that connects the ends of the long side. Since the cross section is arcuate, the sealability of both can be made equal, and a uniform caulking portion is formed over the entire circumference of the battery case opening including the boundary between the arcuate surface and the long side surface. Created by increasing battery internal pressure during charging The safety mechanism such as the current interrupt mechanism in the sealing plate to be activated becomes inoperable due to a decrease in internal pressure due to liquid leakage or gas leakage from the sealing part, and there is no risk of reducing the safety of the battery. A highly reliable battery having excellent properties can be obtained.
[0021]
The same effect can be obtained by inserting a grooved plate from the outer peripheral surface at a predetermined position from the upper end of the opening instead of the reinforcing plate, and inserting and arranging the sealing plate with the groove portion bulged inside as a support portion. .
[0022]
The overall manufacturing process of the battery 1 having the above configuration will be described. The power generation element 3 is accommodated in the battery case 2 having an oval cross-sectional shape, and the reinforcing plate 20 is inserted into the opening of the battery case 2 for positioning. Then, the insulating gasket 4 and the sealing plate 5 are disposed in the opening of the battery case 2 and the filter 8 and one polarity electrode of the power generating element 3 are connected. Finally, the opening of the battery case 2 is connected. The battery 1 is completed by caulking and sealing using the caulking jig 15 as described above.
[0023]
As described above, according to the present embodiment, even in the flat battery 1 having an oval cross-sectional shape, the crimped part 12 that is uniform and excellent in hermeticity can be formed over the entire circumference of the opening, and the battery has a high capacity. As the thickness and thickness of the battery case are reduced, the battery case thickness is reduced and the gasket thickness is reduced, so that a highly reliable sealing state can be realized, and the thin battery 1 with no risk of leakage is obtained. It can be manufactured with high productivity.
[0024]
【The invention's effect】
According to the battery of the present invention and the manufacturing method thereof, even in a flat battery case having an oval cross-sectional shape, it is possible to form a caulked portion that is uniform and excellent in hermeticity over the entire circumference of the opening, and is highly reliable. Since the sealing is performed, it is possible to obtain a battery which is excellent in safety and has no fear of leakage.
[Brief description of the drawings]
FIG. 1 shows a battery according to an embodiment of the present invention, where (a) is an overall perspective view and (b) is an enlarged perspective view showing a sealed state.
2 is a partial enlarged cross-sectional view taken along the line AA in FIG. 1;
3 is a partial enlarged cross-sectional view taken along the line BB in FIG. 1. FIG.
4A and 4B show a caulking jig used in the battery manufacturing process of the embodiment, wherein FIG. 4A is a plan view, FIG. 4B is an enlarged cross-sectional view taken along the line CC of FIG. 4A, and FIG. It is a DD arrow partial expanded sectional view of).
5A and 5B show a caulking jig used in a manufacturing process of a conventional battery, wherein FIG. 5A is a plan view, FIG. 5B is an enlarged cross-sectional view taken along the line E-E in FIG. It is a FF arrow partial expanded sectional view of.
FIG. 6 is a perspective view showing a sealing state of a battery of a conventional example.
FIG. 7 is a partial plan view showing a problem of a sealing state of a battery of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery 2 Battery case 2a Edge part 2b of a long side Edge part 3b of a circular arc surface Power generation element 4 Insulation gasket 5 Sealing plate (sealing member)
12 Caulking portion 13 Flat caulking portion 13a Flat surface 14 Arc caulking portion 15 Caulking jig 17 Arc forming surface 18 Flat forming surface

Claims (3)

A step of housing the power generation element in a battery case having an oval cross-sectional shape, a step of placing a sealing member through a gasket in the opening of the battery case, and a sealing for caulking the opening of the battery case inward In the battery manufacturing method comprising the steps, the edge of the long side surface of the battery case in the sealing step is caulked with a molding surface having an arc-shaped cross section, and the edge of the arc surface connecting between both ends of the long side surface is flat. Manufacturing method of caulking with a shaped molding surface. The sealing case edge of the long side surface of the battery case obtained by the battery manufacturing method according to claim 1 has a flat top portion, and the edge portion of the arc surface connecting the both side ends of the long side surface has an arcuate cross section. Is a battery. The battery according to claim 2, wherein the edge of the arcuate surface connecting the ends of both sides of the long side is higher than the edge of the sealing side of the long side of the battery case.

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